Both my kids are on Facebook, but I closely monitor it and both have loads of adult friends that I know would let me know in a heart beat if my kids posted something stupid that I missed. In fact I had a friend call me up in a panic because he misunderstood a vague post my daughter had made. She was posting about how sad she was about the death of her pet bird, but he misread it and thought she was thinking of killing herself.  
But I have to say that the murder around the corner has served as a wake up call to lots of the other parents in my town. When I'm checking out Rose or DJ's pages, I can read what the other kids are posting and most are complaining about their parents being nosey. LOL 
Ida